BeagleBoardPkg: Introduce macro EDK2_SECOND_STAGE_BOOTOLADER

BeagleBoardPkg: Introduce macro EDK2_SECOND_STAGE_BOOTOLADER

By setting this macro, the OMAP353x header is stripped from the UEFI firmware.
Some boot loader (eg: x-loader) loads the second stage boot loader (u-boot or
uefi) to a specific address and start the firmware from this address.
This macro ensures the reset vector is located at the beginning of the image.

To build the BeagleBoard with ./build.sh to enable this feature:
./build.sh -D EDK2_SECOND_STAGE_BOOTOLADER=1

Note: in this case, you must use BEAGLEBOARD_EFI.fd (and not
BeagleBoard_EFI_flashboot.fd)

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11995 6f19259b-4bc3-4df7-8a09-765794883524